The invention relates to improvements in methods of and in apparatus for disposing of certain bulky commodities, such as refrigerators, freezers and other cooling units. More particularly, the invention relates to improvements in methods of and in apparatus for disposing of commodities which consist of or contain polyurethane foam wherein the cells confine fluorochlorohydrocarbon gas. Still more particularly, the invention relates to improvements in methods and apparatus which can be practiced and utilized with advantage to dispose of pretreated cooling units, particularly cooling units which are devoid of lubricant and refrigerant.
The number of discarded cooling units in industrialized countries is growing at a staggering rate from year to year. For example, the number of cooling units which are discarded per annum in the territory of former Western Germany is well above two million. These discarded cooling units take up approximately 650,000 cubic meters of space which amounts to a volume of approximately 325,000 cubic meters when the discarded cooling units are transferred to garbage dumping grounds. This is the presently prevailing mode of finally disposing of useless cooling units.
Mere dumping of damaged, destroyed, antiquated and other useless cooling units at garbage disposal grounds constitutes a procedure which is objectionable and outright unacceptable for a number of important reasons. First of all, such cooling units contain many substances which contribute to contamination of the atmosphere as well as of waters and of the soil. Secondly, mere dumping of useless cooling units at garbage collecting locations constitutes an unacceptable waste of valuable materials including plastics, metals and others. Recovery of such valuable materials is necessary for several reasons, such as savings in materials as well as a reduction of space requirements of those parts of cooling units which cannot be recycled for renewed use or to promote their disintegration without affecting the atmosphere, the waters and/or the ground.
A typical discarded cooling unit (such as a refrigerator or freezer) normally contains large quantities of recoverable metallic and plastic materials. In addition, such typical cooling unit contains substantial quantities of materials which are pollutants of the atmosphere, soil and/or water. For example, a standard cooling unit is likely to contain 140 grams of coolant or refrigerant (e.g., R12) which is caused to circulate in the cooling circuit of an operative cooling unit and contains fluorochlorohydrocarbon gas. In addition, a typical cooling unit will contain approximately 300 grams of compressor oil which is contaminated with fluorochlorohydrocarbon gas and is confined in the compressor of the cooling unit, as well as between 300 and 1000 grams of fluorochlorohydrocarbon gas (R 11) in the cells or pores of polyurethane foam which is used in cooling units as an insulating material. The gas in the cells of polyurethane foam in a cooling unit which is discarded at a dumping ground in the presently known or customary manner will escape for a period of years to be released into the atmosphere and/or to seep into the soil during progressive decomposition of polyurethane foam.
Certain communities, cities and other political entities have established stringent rules and regulations to remedy the just outlined unsatisfactory situation resulting from dumping of useless cooling units by requiring at least partial treatment of cooling units prior to dumping at the waste collecting facilities. For example, it is already known to remove or expel coolants and lubricants (such as compressor oil) from useless cooling units. Reference may be had to commonly owned copending patent application Ser. No. 07/487,029 filed Feb. 28, 1990 for "Apparatus for evacuating flowable media from discarded refrigerators and the like". It was also proposed to remove the motor, the compressor and certain other (particularly movable) parts prior to dumping of a useless cooling unit.
The just described treatment constitutes a giant step in the right direction. However, such preliminary treatment will normally result in controlled disposal of approximately 40 percent of deleterious ingredients which should be prevented from reaching the atmosphere, the waters and/or the soil in order to avoid serious pollution of the environment. The heretofore known preliminary treatment of cooling units which are about to be discarded is particularly unsatisfactory as far a the insulating material (polyurethane foam with cells which contain entrapped fluorochlorohydrocarbon gas) is concerned.
It was also proposed to simply burn partially treated or pretreated disposable cooling units. Such mode of disposing of cooling units constitutes an irresponsible waste of valuable recoverable materials and is equally unacceptable for ecological reasons. Combustion of cooling units invariably results in the escape of large quantities of dangerous pollutants into the atmosphere. Furthermore, experts in the field of disposing of various synthetic materials warn against combustion of polyurethane foams in incinerators because such combustion results in the development of dangerous dioxane, especially if the combustion takes place at temperatures below 1400.degree. C.
Attempts to expel fluorochlorohydrocarbon gas from the cells of polyurethane foam as a result of heating subsequent to manual or mechanical dismantling and comminution of cooling units, and to thereupon recover the expelled gas, have met with negligible success. Moreover, experts in the relevant field are of the opinion that such mode of treating polyurethane foam is unacceptable because the liberated fluorochlorohydrocarbon gas tends to react with other substances and to form dangerous gaseous pollutants. Furthermore, it has been found that heretofore known methods of recovering fluorochlorohydrocarbon gas from polyurethane foam can ensure a mere partial recovery of as little as 40 percent and not more than 80 percent of fluorochlorohydrocarbon gas.
In accordance with a known proposal, a pilot plant was set up to heat polyurethane foam which was recovered from manually dismantled cooling units. The pilot plant was equipped with means for heating recovered polyurethane foam to a temperature of 170.degree. C., the particles of foam were comminuted as a result of bombardment with steel balls, and this resulted in the release of R11 gas from the cells of foam particles. A drawback of such pilot plant is that its output is very low, the cost of disposing of polyurethane foam and of the gas in its cells is very high, and the treatment involves danger to the attendants and to the plant, primarily due to the need to heat polyurethane foam.
It was also proposed to mechanically dismantle the cooling units and to grind and thereupon heat the collected polyurethane foam. Such treatment was intended to result in expulsion of gases from the cells of the particles of foam. A drawback of this method is that it is dangerous, primarily due to the need for heating the foam.
In accordance with still another proposal, the treatment of polyurethane foam does not involve any heating. The first step includes evacuation of refrigerant and lubricant, and such step is followed by shredding of cooling units in a space which is sealed from the surrounding atmosphere. Shredding is followed by classification to segregate ferrous and nonferrous metals from other constituents prior to briquetting of other constituents which normally include foam and other nonmetallic substances. The briquetting operation is carried at a very high pressure which is supposed to suffice to ensure expulsion of up to 80 percent of fluorochlorohydrocarbon gas from the cells of polyurethane foam. The thus expelled gas is treated in a condensing plant. The apparatus which is used for the practice of the just outlined method is very complex, bulky and expensive. In addition, recovery of up to 80 percent of gases from the cells of polyurethane foam does not constitute a solution which is acceptable to ecologists in many countries, states, districts, cities and smaller communities.